1. Field of the Invention
This invention relates to new and useful polyurea compounds including compositions and methods of using the compounds as grease thickening agents.
2. Description of the Prior Art
Prior art greases have generally comprised a petroleum hydrocarbon oil, refined mineral oil or synthetic ester in which thickening agents such as metal salts or soaps are used in such quantities as to give a final grease composition of the desired consistency. Most greases have been formulated with soaps, however, these soaps tend to catalyze the oxidation of the lubricant. Recently, U.S. Pat. No. 3,879,305 has described improved greases having a wide temperature utility and good oxidation stability which are much improved over the greases made using soaps. The greases of this patent were made using a lubricating oil and a thickening quantity of a polyurea made by reacting a monoamine, a diisocyanate and a diamine. The diamine used therein has one amino group attached to each of two hydrocarbyl groups separated by an oxygen or sulfur atom. The method of making the polyureas of U.S. Pat. No. 3,879,305 requires heating the reactants for approximately one hour prior to forming the grease.
U.S. Pat. No. 3,704,321 utilizes polyoxyalkylene bis-thioureas as extreme pressure lubricants in metal working fluids and, particularly, aqueous type fluids. Preparation of these bis-thioureas requires heating a polyether diamineisothiocyanate mixture for several hours. Further, German Offenlegungsschrift No. 2,604,342 describes the preparation of polyurea greases by the reaction of a monoamine, a diamine and a diisocyanate into a grease.